BAMOS 2021 / 2022 Summer
18 BAMOS Flashback
Terry Hart AMOS History Special Interest Group
Learning to trust weather satellites
Just over sixty years ago , the first images from weather satellites were made . Australian meteorologists were quick to recognise the potential of satellite information and to engage with international agencies in advocating for the synoptic meteorology community , especially those in the southern hemisphere . They were also quick to exploit whatever data became available , initially receiving satellite photos by airmail from the US and later through coded cloud analyses (‘ nephanalyses ’).
The first series of weather satellites , the TIROS ( Television Infrared Observation Satellite ) series of satellites commenced in April 1960 . They were equipped with black and white television cameras , and in some cases also with scanning infrared radiometers .
Bill Gibbs ( 1961 ) reported on some early investigations on the utility of satellite images , based mainly through nephanalyses from TIROS I , but also on a few photographs . He found cases , particularly tropical cyclones or fronts and troughs , where the cloud analyses and images gave valuable insights , but other cases where there seemed little relationship between the nephanalysis and the synoptic pattern . He was concerned about ambiguities in the interpretation of the satellite data and concluded that “ a great deal of work remains to be done in determining the significance of cloud pictures and their relationship to synoptic features ”.
It is salutary , from our perspective , to note that the introduction of satellite did not have the immediate decisive impact that we may have expected . Due to communications limitations from the US , these early investigations were based mainly on coded cloud analyses . Direct readout of satellite imagery did not commence in Australia until 1964 . The TIROS instruments also had intrinsic limitations such as low horizontal resolution , compressed brightness scale and uncertainties in geolocation .
Despite these background misgivings , George Rutherford gave an optimistic review of the applications of satellites to meteorology at the ANZAAS conference in Brisbane in 1961 . He noted the difficulties in the interpretation of satellite data but outlined the great potential , looking beyond imagery to the possibility of vertical temperature sounding from the infrared radiometer channels , and measurement of temperatures of cloud top or sea surface . He also welcomed the opportunities that satellite data offered for improvement in understanding of atmospheric processes .
In 1961 the Bureau coordinated an experiment to validate observations from satellite . Cloud reports from an augmented network of ground weather stations , observations by trained meteorological staff in aircraft and photographs from a highaltitude balloon were combined to prepare an analysis of clouds against which images over the same area from an approximately coincident TIROS III satellite could be validated . Marcel van Dijk and George Rutherford ( 1962 ) describe this inter-comparison experiment conducted on 9 August 1961 over a cut-off low over south-eastern Australia .
Some Bureau staff made observations from commercial flights , but others flew on two Canberra bombers allocated by the RAAF to obtain time-lapse photographs from about 40,000 feet on a track approximately along the line of the satellite . A Melbourne University team led by Vic Hopper launched a high-
Figure from van Dijk and Rutherford ( 1962 ) shows the synoptic map for 0500 UTC on 9 August 1961 , with the location of ground observation points , location of the high-altitude balloon launch , flight paths of the Canberra aircraft and the track of the satellite ( with the points to the right of the track indicating the central location of images ).